This work is a corpus based study focused on a new genre: Web 2.0 encyclopaedias. In particular, the attention is focused on the English edition of Wikipedia, a multilingual, web-based, co-authored enclyclopedic project. Findings of this study show to what extent Wikipedia's co-authored articles prove to be formal and standardized in a way not very dissimilar from Encyclopaedia Britannica online. By contrast, talk pages and WikiSpeak, can be considered a new writing space where a novel variety of the Netspeak Jargon is conveyed. Encyclopedic articles and Wikilanguage, talkpages and Wikispeak, can be considered, in Mc Luhans terms, the "medium and the message" of the new Web 2.0 collaborative environments. Thanks to them a new computer Mediated Discourse Community with its specific linguistic peculiarities is coming to life.